Electronic devices are known which operate with a portable, removable user card having an integral microprocessor, a memory element, or both. Examples of such electronic devices include automated teller machines (ATM), pagers, personal digital assistants (PDA), and radiotelephones, such as cellular telephones and cordless telephones. Examples of removable user cards include a subscriber identity module (SIM) which is used in portable cellular telephones to communicate with a base station under specifications such as the Global System for Mobile Communication (GSM) specification. Other examples of removable user cards include electronic debit cards (electronic cash), and bank or credit cards.
A difficulty in providing electronic devices that operate with a removable portable user card is that the cards and the portable electronic devices each have different optimum size criteria. It is desirable for the user cards to be the size of a standard bank card of the type used with an ATM. Although these user cards are small enough to be carried in wallets and purses, they are sufficiently large that people do not typically lose them.
Portable electronic devices must be small enough that people can easily transport them. This is particularly true for pagers, cellular telephones, and PDAs, where portability is a principal design objective. Preferably, a portable device fits easily into a shirt pocket or purse, or clips onto a person's belt, without discomfort to the wearer.
A limiting factor in reducing the size of portable communication devices is that the user interface must be sufficiently large that people enjoy using the device. A user interface employing a keypad must be large enough that a user routinely presses only the desired key when entering information via the keypad. A display needs to be large enough that it is easily read. Meeting these criteria in ever shrinking devices is an increasing challenge to industrial designers.
An additional difficulty is that although people desire smaller devices, they desire that these devices perform more functions. People like to carry as few devices as possible. Thus the ability to carry a single electronic device to provide all personal communication needs, such as paging and cellular communication, as well as connectivity with network systems such as banking systems, investment networks, and the internet, is considered desirable.
It is therefor highly desirable to achieve more versatile portable communication devices having smaller sizes even though the cards with which they are used remain a larger standard size. Because an effective solution has not been found for accommodating cards in a device smaller than the card, the size of the cards has become a limiting factor in the efforts to make devices smaller. Although designers can choose not to use certain cards, the functionality of the device is restricted if it can not use all common, standard sized cards.
Therefor, it is desirable to provide cards that provide more flexibility for readily portable devices.